The research, which is published in the current issue of Nature, found that HIV began spreading between 1884 and 1924, around the same time urban centers in west central Africa were established. This estimated time of origin is decades earlier than the previous estimate of 1930.

Although acquired immune deficiency syndrome (AIDS) didn't hit mainstream collective consciousness until the early 1980s, new research out of the University of Arizona in Tucson indicates that the most pervasive global strain of human immunodeficiency virus (HIV) began spreading among humans between 1884 and 1924, a finding that suggests growing urbanization in colonial Africa set the stage for the HIV/AIDS pandemic.

Michael Worobey, an assistant ecology and evolutionary biology professor at Arizona, led the research, which studied a number of HIV-1 (the strain found in most cases outside of Africa) genetic sequences to determine the time periods when the virus genetically diverged from its predecessors. These findings, published in the current issue of Nature, were mapped out in the form of a family tree whose roots date back to the beginning of the 20th century.

The research, co-sponsored by the National Institute of Allergy and Infectious Diseases (NIAID), part of the U.S. National Institutes of Health, included a team of scientists from four continents who screened multiple tissue samples and uncovered the world's second-oldest genetic sequence of HIV-1 group M, which dates from 1960. The scientists used that, along with dozens of other previously known HIV-1 sequences, to construct a range of plausible family trees for this viral strain.

A biopsy taken from an African woman nearly 50 years ago contains traces of the HIV genome, researchers have found. Analysis of sequences from the newly discovered sample suggests that the virus has been plaguing humans for almost a century.

Although AIDS was not recognized until the 1980s, HIV was infecting humans well before then. Researchers hope that by studying the origin and evolution of HIV, they can learn more about how the virus made the leap from chimpanzees to humans, and work out how best to design a vaccine to fight it.

... Their results showed that the most likely date for HIV's emergence was about 1908, when Léopoldville was emerging as a centre for trade. [See full text]